1. Field of the Invention
The present invention relates to a supporting apparatus, an exposure apparatus, and a device manufacturing method.
2. Description of the Related Art
FIG. 12 is a perspective showing a positioning apparatus used in, e.g., an electron beam exposure apparatus disclosed in Japanese Patent Laid-Open No. 2004-349576. FIG. 13 is a sectional view showing the schematic arrangement of a static pressure fluid bearing unit in the positioning apparatus shown in FIG. 12.
For example, a sample holder 65, on which a sample (not shown), such as a semiconductor wafer, is mounted, is set on a sample supporting mechanism 66. An X-Y stage 67 translates the sample holder 65 within an X-Y plane. It is assumed that a stage apparatus is used in a vacuum atmosphere, or the like. When an external fluid supply source (not shown) supplies a fluid, such as air, to feed the fluid with a predetermined pressure to a portion between static pressure fluid bearings 64b and a movable guide 63, the static pressure fluid bearings 64b axially support the movable guide 63 by levitation. A vacuum pump (not shown), connected outside a vacuum container, recovers the fluid injected from the static pressure fluid bearings 64b through labyrinth pockets 64p. 
When the movable guide 63 moves, those portions of the movable guide 63, which are supported by the static pressure fluid bearings 64b, change. This causes a shift between the points of action with respect to the movable guide 63 by the static pressure fluid bearings 64b and the barycenter of the movable guide 63, to generate moments indicated by arrows in FIG. 13. Consequently, the gap between the movable guide 63 and static pressure fluid bearings 64b fluctuates. If acceleration or deceleration further acts on the movable guide 63 or if the movable guide 63 stops urgently, the static pressure fluid bearings 64b come into contact with the movable guide 63 and break, in the worst case.